This story says that about 1500 child abuse investigations in North Texas are closed each year because the families being investigated move and don't leave forwarding addresses. It then details the efforts officials make in trying to locate the family. Then it basically blames privacy laws that prevent one branch of the government from accessing records held by a separate branch and says those laws are "something that could be fixed".

Collection agencies and advertisers are apparently able to track you to the ends of the earth without violating privacy laws. My wife still gets stuff addressed to her maiden name at our home, even though this is the 3rd place we've lived since we got married. If private companies can do this without needing to remove privacy safeguards on government information, why can't CPS?